Case Study: Modernizing Controls on a Stacking Crane








An automotive assembly plant operated an automatic sheet metal storage and retrieval system to manage stamped parts between their stamping and welding departments. Although the system provided valuable utilization of storage with limited floor space, its outdated control system was cumbersome to maintain and the availability of replacement parts was becoming a concern. ONYX was called on to modernize and improve the reliability of the system.







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The Problem

Older controls on the equipment did not provide plant maintenance teams the ability to troubleshoot the outdated logic controller. To maintenance personnel it was a 'black box' and the availability of spare parts and vendor support was declining. Significant downtime was contributed to device failures and inability to troubleshoot the system. Goals for the system included reducing hardware replacement costs, decreasing MTTR (mean time to repair) and improving ease of use for the often-used crane operator interface.

The Solution

A modern PLC (programmable logic controller) based control system was implemented with advanced VFD (variable frequency drives) replacing the 'black box' logic controllers and outdated drives for the cranes. ONYX Engineering updated the point of operation with a new Human-Machine Interface (HMI) that improved system recovery through a convenient troubleshooting interface. All components used were commercially available with vendor supported controls components. The crane's optical modem for communication with control room was also upgraded to a newer version.

The Results

The Crane Control System upgrade significantly improved the uptime and MTTR of the existing storage and retrieval system. With a user-friendly HMI in place and easy to troubleshoot PLC and VFD systems the overall system availability was increased and the cost to operate was decreased.

Project Details



About 3 months




                   Client: 1                                                      

Onyx: 2 Engineers





Services Provided

Control engineering and design

PLC/HMI programming

AutoCAD documentation 

Start-up and commissioning 





Mitsubishi QCPU PLC

Mitsubishi GT25 HMI

Mitsubishi A840 Inverter VFD

Serial RS-232, EtherNet/IP

Toyo Electric Modem